Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

2040-07-03astronomy score per night — click a bar for that night2040-08-01

night of	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-07-03 Tue	—	unknown	—	42.9° 12:10	4.6	25%	47.1°
2040-07-04 Wed	—	unknown	—	42.9° 12:05	4.63	17%	38.9°
2040-07-05 Thu	—	unknown	—	42.9° 12:00	4.66	10%	32.9°
2040-07-06 Fri	—	unknown	—	42.9° 11:55	4.69	5%	30.3°
2040-07-07 Sat	—	unknown	—	42.9° 11:50	4.72	2%	31.9°
2040-07-08 Sun	—	unknown	—	42.9° 11:45	4.75	0%	37.0°
2040-07-09 Mon	—	unknown	—	42.9° 11:45	4.79	0%	44.4°
2040-07-10 Tue	—	unknown	—	42.9° 11:40	4.82	2%	53.1°
2040-07-11 Wed	—	unknown	—	42.9° 11:35	4.86	6%	62.6°
2040-07-12 Thu	—	unknown	—	42.9° 11:30	4.9	11%	72.6°
2040-07-13 Fri	—	unknown	—	42.9° 11:25	4.94	18%	82.9°
2040-07-14 Sat	—	unknown	—	42.9° 11:25	4.98	26%	93.5°
2040-07-15 Sun	—	unknown	—	42.9° 11:20	5.02	35%	104.2°
2040-07-16 Mon	—	unknown	—	42.9° 11:15	5.07	45%	114.9°
2040-07-17 Tue	—	unknown	—	42.9° 11:10	5.11	56%	125.5°
2040-07-18 Wed	—	unknown	—	42.9° 11:05	5.16	66%	135.5°
2040-07-19 Thu	—	unknown	—	42.9° 11:05	5.21	77%	144.1°
2040-07-20 Fri	—	unknown	—	42.9° 11:00	5.25	86%	149.1°
2040-07-21 Sat	—	unknown	—	42.9° 10:55	5.3	93%	148.5°
2040-07-22 Sun	—	unknown	—	42.9° 10:50	5.35	98%	142.0°
2040-07-23 Mon	—	unknown	—	42.9° 10:50	5.4	100%	131.9°
2040-07-24 Tue	—	unknown	—	42.9° 10:45	5.45	99%	120.0°
2040-07-25 Wed	—	unknown	—	42.9° 10:40	5.5	95%	107.5°
2040-07-26 Thu	—	unknown	—	42.9° 10:35	5.56	88%	94.9°
2040-07-27 Fri	—	unknown	—	42.9° 10:30	5.61	80%	82.6°
2040-07-28 Sat	—	unknown	—	42.9° 10:30	5.66	70%	70.8°
2040-07-29 Sun	—	unknown	—	42.9° 10:25	5.72	60%	59.8°
2040-07-30 Mon	—	unknown	—	42.9° 10:20	5.77	49%	49.7°
2040-07-31 Tue	—	unknown	—	42.9° 10:15	5.83	39%	40.9°
2040-08-01 Wed	—	unknown	—	42.9° 10:10	5.88	30%	34.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-07-03&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.